Such a record carrier and apparatus are known from European Patent Application EP 0 727 779, document D1 in the list of related documents. The document discloses a record carrier in the form of an optical disk having a spiral pattern of grooves and lands on a substrate, constituting substantially parallel recording tracks. The recording tracks are subdivided in longitudinal direction into recording units, wherein a section of a groove or land serves as recording area, which section is preceded by an address area comprising pre-recorded address marks, called pre-pits. The address marks represent address information for positioning a recording head on a desired track and are indicative for the address of the recording area following the address area. In a direction transverse to the tracks the address marks are disposed in between the recording tracks, i.e. in between the virtual centre-lines of the recording tracks comprising said optically readable marks. In longitudinal direction the address marks are positioned in the address area, i.e. in a flat area interrupting the groove/land pattern, on a virtual extension of the boundary between a groove and a land. When scanning a track a radiation spot is centred on the track and the address marks are detectable off-centre, i.e. at a distance in a direction transverse to the tracks, on both sides of a virtual extension of the centre line of the track in the address area. So the address marks are shared by adjacent tracks and are readable equally well from both adjacent tracks. The address area is divided longitudinally in portions, and first address marks shared with the track on one side are in a portion of the address area called a sharing portion, and a further sharing portion comprises second address marks shared with the track on the other side. The apparatus comprises an optical system for recording or reading information by generating a spot via a radiation beam on a track of the record carrier. The record carrier is rotated and the spot is positioned in radial direction on the centre of the track by tracking means for scanning the track. During scanning the first address marks are read from the first sharing portion, and thereafter the second address marks are read from the further sharing portion and the address information is recovered. Tracking offset is detected by comparing the read signals from the first and second sharing portion, e.g. by comparing the amplitude of said read signals of the address marks. For detecting the tracking offset it is required that the address marks are positioned off-centre, because the read signal of such address marks will increase if the spot has an offset to that side and decrease if the offset is to the other side. Inherently, the read signal of the address marks is rather weak, because the spot is centred on the track and the address marks are off-centre. A stronger read signal would be available if address marks were positioned on the centre line, but centred address marks cannot easily be used to generate an offset signal, because the read signal decreases similarly for offsets to both sides. So the known record carrier and apparatus have the problem, that the address marks are off-centre and generate a weak and noisy read signal, and therefore errors in the recovery of the address information may occur.